/*
 * Copyright (c) 2021 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * helper to wait for all callbacks to complete; similar to `Promise.all`
 * exposed to metrics object for unit tests
 * @param {Array} requests
 * @param {Function} handler
 * @param {Function} callback
 */
var asyncAll = function (requests, handler, callback) {
    var total = requests.length,
        errors = null,
        results = [],
        done = function (err, result) {
            if (err) {
                // errors are `null` unless there is an error, which allows for promisification
                errors = errors || [];
                errors.push(err);
            }
            results.push(result);
            if (--total === 0) {
                callback(errors, results)
            }
        };

    if (total === 0) {
        callback(errors, results);
    } else {
        for (var i = 0, l = requests.length; i < l; i++) {
            handler(requests[i], done);
        }
    }
};

/**
 * Validate type of time property, and convert to Unix timestamp if necessary
 * @param {Date|number} time - value to check
 * @returns {number} Unix timestamp
 */
var ensureTimestamp = function (time) {
    if (!(time instanceof Date || typeof time === 'number')) {
        throw new Error('`time` property must be a Date or Unix timestamp and is only required for `import` endpoint');
    }
    return time instanceof Date ? Math.floor(time.getTime() / 1000) : time;
};

const Base64 = {
    // private property
    _keyStr: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=',

    // public method for encoding
    encode: function (input) {
        let output = '';
        let chr1, chr2, chr3, enc1, enc2, enc3, enc4;
        let i = 0;

        input = Base64._utf8Encode(input);

        while (i < input.length) {

            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);

            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;

            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }

            output = output +
            Base64._keyStr.charAt(enc1) + Base64._keyStr.charAt(enc2) +
            Base64._keyStr.charAt(enc3) + Base64._keyStr.charAt(enc4);

        }

        return output;
    },

    // public method for decoding
    decode: function (input) {
        let output = '';
        let chr1, chr2, chr3;
        let enc1, enc2, enc3, enc4;
        let i = 0;

        input = input.replace(/[^A-Za-z0-9+/=]/g, '');

        while (i < input.length) {

            enc1 = Base64._keyStr.indexOf(input.charAt(i++));
            enc2 = Base64._keyStr.indexOf(input.charAt(i++));
            enc3 = Base64._keyStr.indexOf(input.charAt(i++));
            enc4 = Base64._keyStr.indexOf(input.charAt(i++));

            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;

            output = output + String.fromCharCode(chr1);

            if (enc3 != 64) {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64) {
                output = output + String.fromCharCode(chr3);
            }

        }

        output = Base64._utf8Decode(output);

        return output;

    },

    // private method for UTF-8 encoding
    _utf8Encode: function (string) {
        string = string.replace(/\r\n/g, '\n');
        let utftext = '';

        for (let n = 0; n < string.length; n++) {

            let c = string.charCodeAt(n);

            if (c < 128) {
                utftext += String.fromCharCode(c);
            }
            else if ((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            }
            else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }

        }

        return utftext;
    },

    // private method for UTF-8 decoding
    _utf8Decode: function (utftext) {
        let string = '';
        let i = 0;
        let c = 0;
        let c2 = 0;
        let c3 = 0;

        while (i < utftext.length) {

            c = utftext.charCodeAt(i);

            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            }
            else if ((c > 191) && (c < 224)) {
                c2 = utftext.charCodeAt(i + 1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            }
            else {
                c2 = utftext.charCodeAt(i + 1);
                c3 = utftext.charCodeAt(i + 2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }

        }
        return string;
    }
}

export { asyncAll, ensureTimestamp, Base64 }
